Piping systems, vessels and associated apparatuses are used extensively in many industrial applications wherein fluids and other substances are used, produced or transformed. In certain industries, such as for example pharmaceutical industries and food processing industries, including non-limitatively the dairy industry, cleanliness is of utmost importance and is governed by strict regulatory requirements and standards.
Accordingly, the cleaning of corresponding piping systems, vessels and associated apparatuses must be performed regularly or daily to maintain sanitary standards and to meet strict regulatory requirements. Furthermore, piping systems, associated vessels and associated apparatuses may also require cleaning to permit maintenance thereon and, in some cases, subsequently to such maintenance.
Still furthermore, there exist a plurality of situations wherein fluids used during a given production cycle must be removed from industrial piping systems, vessels and associated apparatuses. For example, in the food processing industry, process fluids need to be removed from some sections or all of the hydraulic circuitry when the circuitry is used for processing a different type of products, or even the same type of products in a different flavour, so as to avoid contamination between products or flavors.
To meet cleanliness requirements and to allow for adequate product and/or flavor separation during processing thereof in the most effective and cost efficient manner, most processing facilities have installed so-called “clean-in-place” (CIP) systems. These CIP systems are often permanent, fixed hard piped systems which operate quickly and reduce temporary installation such as temporary hoses, pumps and the like.
Conventional CIP systems typically include a number of tanks, silos or vessels, associated pumps and valves and interconnecting piping. The conventional clean-in-place systems generally fall in three categories. The first category is the so-called single use category in which the chemical cleaning agent is used once and discarded after use. The second category is the so-called multiple use category in which the chemical cleaning agent is stored after use and subsequently reused for system cleaning. The third category is a combination of both categories.
Regardless of the type of system used, in the food processing industry such as in the dairy industry, the piping system, silos and associated apparatuses such as the filtration apparatuses, the dryers, the mixers, evaporators, pasteurizers, separators, filters, pumps and the like must be periodically cleaned, rinsed and sanitized, disinfected or sterilized so as to be maintained in a satisfactory sanitary condition. Generally speaking, a typical cleaning operation involves an initial rinse cycle using clean or recovered rinse water, a subsequent detergent wash cycle using a detergent solution, a post rinse cycle and a final germicidal step using a sanitizing, asepticising, disinfecting or sterilizing solution. If that solution has a “no rinse” approval at the recommended use concentration no further rinse is required. If there is no such approval, a final rinse must be done with sterile water. In some cases, a last step of drying, draining or performing an air blow with sanitary air is finally performed.
Whether the processed liquid needs to be washed out of the overall circuitry in order to make place for a different product or flavor or for cleaning purposes, five conventional methods are typically used. In accordance with a first prior art method, water is added to the circuitry upstream and is pushed at the back of the processed liquid with the use of the same pumping apparatuses used for processing until it reaches a downstream target location.
The volume of water being pumped is measured using a flow meter or by time. Once the measured volume of water has been pumped throughout the circuitry, the outflow is deviated towards a drain or towards a recuperation tank for further use in the process when possible. Rinsing is then continued towards the drain until clear water flows out of the circuitry.
There are several other ways to make a product recovery at end of process. For example, instead of using a flow meter, the product recovery after end of process is also done in the industry using either a conductivity meter or a turbidity meter or an optometer. That apparatus is normally installed at the end of the circuitry. The water is pumped or pushed at the beginning of the circuitry and the analyser (conductivity meter, turbidity meter or optometer) controls the destination of the fluid (to the further process or to a recovery tank or to drain) based on the set point that was preset. In both cases (this one and the one using a flow meter), the disadvantages are the same. There is still a considerable amount of water used.
A large amount of water is used to push the product being cleaned out of the circuitry. The greater the size of the circuitry or piping system, the greater the volume of water required as there will be an important dilution factor.
In situations wherein the push out of a given product is performed between two types of products, the inverse procedure must also be performed. Indeed, the second product will be used to push the water downstream. In such instances, water flows towards the drain until there is a noticeable phase change or cut. Because of the dilution factor, the phase change or cut does not happen sharply and, hence, the product-water mixture must be deviated towards the drain until there is the downstream flow of substantially pure product (without any significant dilution).
When the cleaning of the circuitry is being performed, the same type of steps must be used to bring the disinfecting or washing liquid into the circuitry and also to push the latter out of the circuitry. In other words, between each phase, water is used to eliminate food product or washing product residues, which also causes a relatively large amount of water to be used. In addition, in some cases the returning water and residues needs to be treated before being released, which results in relatively large costs due to the relatively large quantity of returning water and residues to process.
A third method for pushing a fluid out of a circuitry involves the use of pressurized air. Pressurized air is introduced upstream in the circuitry in order to push the liquid downstream. This method is mainly used in situations prohibiting the mixing of water and the product.
The use of pressurized air is responsible for numerous drawbacks. For example, incorporating air into the product may result in oxidizing the final product and, hence, altering its taste and its expected lifetime. Also, incorporation of air in the product may result in the production of foam, which may render the process inaccurate.
Furthermore, the use of air to push the product downstream may create preferential pathways in the piping system. Part of the product only is then pushed out of the circuitry. Accordingly, there is a loss of product since the air is often unable to push all of the product downstream, particularly in situations wherein there are changes in piping diameter and wherein there exists vertical piping in certain areas, which is often the case.
A fourth principle used in product recovery includes the use of a so-called “pig system”. The recovery is done using some kind of recovery device, such as for example a cork, a plug or a ball that fits and can slide into the pipe from an insertion point A to an outlet point B. After the end of process, the recovery device is inserted at the beginning of the process circuitry via a Y type of pipe with pressurized air. That same air then pushes this recovery device from point A until it reaches point B, and then through a an outlet including a Y type of pipe again. That system is mainly seen in applications where the product to move out is viscous.
However, that principle is rarely seen because of the following drawbacks:                i. the recovery device can become stuck in the pipe, which sometimes even require that the pipe be cut for recovery of the recovery device;        ii. to identify where the recovery device may become stuck, the recovery device typically contains a magnet and, outside the pipe, magnet detectors are installed along the pipe, this results in a relatively expensive cleaning system;        iii. the recovery device is practically only usable in pipes of substantially constant diameter with no protruding valve. As soon as the circuitry has valves, plates, pumps, filters or any other process equipment, this principle can't be used; and        iv. curved pipes need to have relatively large radius of curvature, which is relatively expensive and can present a problem of space in the plant.        
A fifth principle used in the cleaning of pipes includes solid granules mixed with fluids. The fluid and granules mixture are either pushed with a pressurized gas or pulled through a partial or total vacuum. However, in this method the granules complicate an eventual recovery of food residues that are washed using this fifth principle. Furthermore, this principle cannot typically be used to clean processing equipment in which vessels are equipped with spray devices because the granules may plug the vessel spray device, or they can settle at the bottom of the vessel and be relatively hard to dislodge.
Also, systems using this principle are relatively complex and therefore relatively expensive and relatively more prone to malfunction than systems wherein only a fluid is used. Furthermore, before being reused, if such a reuse is desired, the granules typically need to be washed and disinfected.
Accordingly, there exists a need in the industry for an improved cleaning method and apparatus for use with piping systems, vessels and associated equipment.